Higher Tier: Half Equations for Aqueous Electrolysis
Part of Electrolysis of Aqueous Solutions — GCSE Chemistry
This higher tier covers Higher Tier: Half Equations for Aqueous Electrolysis within Electrolysis of Aqueous Solutions for GCSE Chemistry. Revise Electrolysis of Aqueous Solutions in Electrolysis for GCSE Chemistry with 20 exam-style questions and 0 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 7 of 12 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 7 of 12
Practice
20 questions
Recall
0 flashcards
🎓 Higher Tier: Half Equations for Aqueous Electrolysis
At Higher Tier, you are expected to write and balance half equations for all four possible products in aqueous electrolysis:
Cathode (reduction — gain of electrons):
- Hydrogen:
2H⁺ + 2e⁻ → H₂ - Copper:
Cu²⁺ + 2e⁻ → Cu
Anode (oxidation — loss of electrons):
- Chlorine:
2Cl⁻ → Cl₂ + 2e⁻ - Oxygen:
4OH⁻ → O₂ + 2H₂O + 4e⁻
The oxygen half equation is the most complex — notice that 4 OH⁻ ions produce 1 O₂ molecule and 2 H₂O molecules. Check: 4 oxygens on each side ✓, 4 hydrogens on each side ✓, 4 negative charges = 4 electrons lost ✓.